In December, Amazon(AMZN) said it was looking to use drones to deliver products to customers, though the drones would not be ready to take flight for four or five years.

The online retailer faces innumerable regulatory and logistical hurdles before the idea can take off. The Federal Aviation Administration will have to devise safety rules for unmanned aircraft, but there's little prospect of that happening anytime soon.

The FAA has been reviewing commercial drones since 2009, but it has not yet given them the thumbs up.

Personal drones: Fun toy or spying eye?

Logistics and express delivery group Deutsche Post DHL(DPSGY) has also carried out limited trials.